Guy Whittingham is convinced Marcos Painter will strengthen his leaky Pompey defence.
The former Brighton man yesterday penned a deal until January having impressed on trial this week.
The Blues had been searching for left-back competition for Dan Butler since the start of the campaign and the free agent fits that bill.
Whittingham sees Painter as more of a defensive full-back.
That is in contrast to Butler, who has regularly shown his attacking aspirations since emerging into the first team last season.
And Pompey’s boss believes the 26-year-old’s experience, which includes promotion with Swansea, can also help shore up his rearguard which has conceded seven goals in three matches so far.
Whittingham said: ‘Marcos is a solid defender. I think he brings a bit of experience into our back line.
‘Our purpose in the summer was to go out and recruit players between the age of 21 and 26 who could, if we were successful, come through the leagues with us and I think on the whole we have done that.
‘Probably where we didn’t do well enough and didn’t have cover was left-back.
‘Yes you can put Danny East in there but he is not really a left-back.
‘We needed another out-and-out left-back – one with experience – and Marcos fits the bill.
‘We needed someone who would not necessarily be bombing on because Dan Butler can do that.
‘On the other side Yassin and Danny East can also do that – with Joe Devera more of a sitter.
‘You need all sorts and we needed somebody who is a defender first and foremost.
‘Some say he is also a tough tackler and you need that in this league, for sure.
‘Everybody keeps telling us the physical side of things are going to step up.
‘Probably we are not quite seeing it at the moment until we get into the months where it is going to be a little heavier on the ground, raining and cold.
‘I think Marcos’ experience will come through there.
‘And we see him primarily as an experienced defender.’
Following his departure from Brighton at the end of last season, Painter has trialled at Yeovil and been training with Birmingham.
Whittingham has also cast his eye over him in Pompey training this week.
And believes the defender is ready to be thrown into the first-team squad for tomorrow’s Morecambe visit.
He added: ‘Marcos is fit. He has a good relationship with Lee Clark at Birmingham and they have allowed him to train with the development squad up there – and he’s played a couple of 90 minutes for them as well.
‘We have no worries about putting him straight into the squad.
‘Between him and Danny (East) is a decision we need to make and a decision we have been looking at.’